This invention relates to a distance detector device utilizing the active lighting method with the principle of triangulation in which a variation of the photoelectric output of the light sensitive element is detected to measure a distance between the distance detector device and the object.
In a conventional system, there has been proposed a distance detector device having light projecting means or active lighting means, and a plurality of light sensitive elements each corresponding to a different object distance. In operation, light is projected from the light projecting means to the object, and the distance from the object to the distance detector device is measured by sensing the light sensitive element receiving the highest intensity reflected light from the object.
However, the sensor circuit applied in this system requires a quite complex circuit, and use of a plurality of light sensitive elements requires an increased photoelectric output of each of the light sensitive elements, so that the scale of the circuit for use in comparing the photoelectric outputs with each other or obtaining their maximum valve is substantial.
In turn, there has been also proposed a device for detecting a distance by a method wherein a photoelectric output from a light sensitive element such as a light potentiometer is varied in response to which position a light reflected from the object is incident on said light potentiometer, and thereby detected. However, in this device, a uniform surface resistance of the light sensitive element forming a light potentiometer becomes very important and a method for making the light sensitive element is also specialized, resulting in the element being expensive to manufacture. Further, there has also been found such the disadvantage that a circuit for measuring a distance between the distance detecting device and the object and for generating a linearity of the output signal is complex.
In view of the problems described above, the present invention has been devised.